Module 12 Notes
- Not enough IPs
- More features
- A mechanism for carrying real-time traffic to avoid route changes
- Ability to work with multiple peer servers
- Provide capability for using shared resources
- Networking professionals argue that internet communication follows an hourglass model and that IP lies at the position where the hourglass is thin
- Both are connectionless
- IPv6 packets still self-destruct after crossing a certain number of routers
- Address Size: IPv4 uses 32 bits, IPv6 uses 128 bits
- Header Format: Almost every field in the header has been changed from v4 to v6
- Rather than include fields in the standard header to handle any specific issue that might occur, IPv6 uses a standard header and deals with any optional IP data via extension headers.
- IPv6 header is 40 bytes long (constant format, fixed size) -> reduced processing time
- IPv6 doesn't have a special address for broadcasting
- Colon hexadecimal notation. Each group of 16 bits is written in hexadecimal, with a colon separating each group
- Shortening options:
- Leading zeros can be omitted from each group.
- Old: 3ffe:1900:4545:0003:0200:f8ff:fe21:67cf
- New: 3ffe:1900:4545:3:200:f8ff:fe21:67cf
- A double colon (::) can be used once in an address to replace multiple fields of zeros. This is known as Zero Compression. (can only be used once)
- Old: fe80:0:0:0:200:f8ff:fe21:67cf
- New: fe80::200:f8ff:fe21:67cf
- Leading zeros can be omitted from each group.
- 64 bit network prefix used for routing
- 48 bits for Routing Prefix (16 for subnetting)
- 64 bit interface identifier used to identify a host
- CIDR is preferred for notation
- IPv6 addresses use 128 bits to represent an address which includes bits to be used for subnetting. The second half of the address (least significant 64 bits) is always used for hosts only. Therefore, there is no compromise if we subnet the network.
- 16 bits of subnet is equivalent to IPv4’s Class B Network. Using these subnet bits, an organization can have another 65 thousands of subnets which is by far, more than enough.
- Can further subnet the network beyond 16 bits of Subnet ID, by borrowing host bits; but it is recommended that 64 bits should always be used for hosts addresses because auto-configuration requires 64 bits.
- IPv6 subnetting works on the same concept as Variable Length Subnet Masking in IPv4.